With leaf defoliators, such as the rubber spiral type shown in U.S. Pat. No. 2,834,174, it is common for the tobacco stalks engaged thereby to bend and deflect during the harvesting operation. Sometimes the bending and deflection of the stalks actually results in the stalks being broken or severely damaged. But of equal concern, is that the effectiveness of the defoliators is impaired by the instability or movement of the stalks during defoliation, and the tobacco leaves are not cleanly defoliated from the stalk, and in some cases the leaves may not even be defoliated at all and consequently that portion of the tobacco crop is lost.
In an effort to stablize the stalks during defoliation, the disclosures in U.S. Pats. No. 3,507,103 and 3,841,071 have suggested the use of a pair of driven belts disposed in side-by-side relationship and placed below the defoliators for receiving the tobacco stalks therebetween and engaging such only on opposite sides with a gripping action. While such a stalk gripping design has been effective as far as lateral or side-to-side stability is concerned and has greatly contributed to the overall efficiency of automatic tobacco harvesting as we know it today, it still has been observed that some stalks, especially small and immature stalks, are not always completely stablized in the longitudinal direction between the driven belts. Consequently, in these cases, the efficiency and effectiveness of automatic leaf defoliation is not as good as when the stalk is completely stablized during the defoliating process.
Moreover, the spiral type leaf defoliator referred to above is driven such that the leaves are engaged generally about the upper sides thereof and the rotative action of the defoliators tend to break the leaves from the stalks and the leaves fall downwardly adjacent the stalks of tobacco being harvested. Below the defoliators on each side of the defoliator head is typically found a lateral conveyor assembly for conveying the defoliated leaves outwardly from the stalk row. Occasionally, however, tobacco leaves may fall between the lateral conveyor assemblies and between the stalk gripping belts, and in such cases, this part of the tobacco crop is lost unless picked up by hand.